1,720,996 research outputs found
Supersymmetric corrections to '/ at the leading order in QCD and QED
No full textWe study the corrections to \epsilon^\prime /\epsilon in the minimal supersymmetric model at the leading order in QCD and QED. Supersymmetry can increase the standard model prediction for \epsilon^\prime /\epsilon by at most 40\% for m_t=174 GeV, an enhancement which is indistinguishable from the present theoretical uncertainties. The most conspicuous effect of supersymmetry is a strong depletion of \epsilon^\prime /\epsilon. For certain choices of supersymmetric parameters, vanishing and even small negative values of \epsilon^\prime /\epsilon can be obtained for the top quark in the CDF range.We study the corrections to in the minimal supersymmetric model at the leading order in QCD and QED. Supersymmetry can increase the standard model prediction for by at most 40\% for GeV, an enhancement which is indistinguishable from the present theoretical uncertainties. The most conspicuous effect of supersymmetry is a strong depletion of . For certain choices of supersymmetric parameters, vanishing and even small negative values of can be obtained for the top quark in the CDF range.We study the corrections to in the minimal supersymmetric model at the leading order in QCD and QED. Supersymmetry can increase the standard model prediction for by at most 40\% for GeV, an enhancement which is indistinguishable from the present theoretical uncertainties. The most conspicuous effect of supersymmetry is a strong depletion of . For certain choices of supersymmetric parameters, vanishing and even small negative values of can be obtained for the top quark in the CDF range.We study the corrections to ϵ ′/ ϵ in the minimal supersymmetric model at the leading order in QCD and QED. Supersymmetry can increase the standard model prediction for ϵ ′/ ϵ by at most 40% for m t = 174 GeV, an enhancement which is indistinguishable from the present theoretical uncertainties. The most conspicuous effect of supersymmetry is a strong depletion of ϵ ′/ ϵ . For certain choices of supersymmetric parameters, vanishing and even small negative values of ϵ ′/ ϵ can be obtained for the top quark in the CDF range
QED Logarithms in the Electroweak Corrections to the Muon Anomalous Magnetic Moment
No full textWe employ an effective Lagrangian approach to derive the leading-logarithm two-loop electroweak contributions to the muon anomalous magnetic moment, a_mu. We show that these corrections can be obtained using known results on the anomalous dimensions of composite operators. We confirm the result of Czarnecki et al. for the bosonic part and present the complete sin^2 \theta_W dependence of the fermionic contribution. The approach is then used to compute the leading-logarithm three-loop electroweak contribution to a_mu. Finally we derive, in a fairly model-independent way, the QED improvement of new-physics contributions to a_mu and to the electric dipole moment (EDM) of the electron. We find that the QED corrections reduce the effect of new physics at the electroweak scale by 6% (for a_mu) and by 11% (for the electron EDM).We employ an effective Lagrangian approach to derive the leading-logarithm two-loop electroweak contributions to the muon anomalous magnetic moment, a_mu. We show that these corrections can be obtained using known results on the anomalous dimensions of composite operators. We confirm the result of Czarnecki et al. for the bosonic part and present the complete sin^2 \theta_W dependence of the fermionic contribution. The approach is then used to compute the leading-logarithm three-loop electroweak contribution to a_mu. Finally we derive, in a fairly model-independent way, the QED improvement of new-physics contributions to a_mu and to the electric dipole moment (EDM) of the electron. We find that the QED corrections reduce the effect of new physics at the electroweak scale by 6% (for a_mu) and by 11% (for the electron EDM)
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